One electrophotographic image forming apparatus known in the art includes a plurality of process cartridges, each of which supports a photosensitive drum for a corresponding toner color, e.g., for one of the colors yellow, magenta, cyan, and black.
One such image forming apparatus that has been proposed includes an apparatus body; an image-forming unit that integrally retains a plurality of process cartridges and that is detachably mounted in the apparatus body; a sheet-conveying belt disposed beneath the image-forming unit and in confrontation with the plurality of process cartridges; a belt-cleaning device that removes toner when toner becomes deposited on the sheet-conveying belt; a waste toner collection box that is provided at the image-forming unit and that collects waste toner removed from the sheet-conveying belt by the belt-cleaning device; and a belt-waste-toner conveying tube that is fixed to the apparatus body and that conveys waste toner removed by the belt-cleaning device to the waste toner collection box.
In an image forming apparatus having this conventional structure, the waste toner collection box can be uncoupled from the belt-waste-toner conveying tube. The waste toner collection box is uncoupled from the belt-waste-toner conveying tube when the image-forming unit is pulled out of the apparatus body, and is coupled to the belt-waste-toner conveying tube when the image-forming unit is mounted in the apparatus body.